---
id: "CVE-2026-101801"
kind: "vulnerability"
aliases: ["CVE-2026-101801"]
title: "MySQL Server: optimizer flaw lets a privileged user crash the database"
severity: "medium"
cvss: 4.9
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["database", "mysql", "mysql-cluster", "package", "self-hosted"]
not_affected_if: ["no-privileged-accounts-exposed", "unaffected-version"]
published_at: "2026-10-20T22:18:35+00:00"
first_seen_at: "2026-10-23T21:57:23+00:00"
updated_at: "2026-10-25T04:31:13+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-101801", "first_seen_at": "2026-10-23T21:57:23+00:00"}]
---

# MySQL Server: optimizer flaw lets a privileged user crash the database

A flaw in the MySQL Server optimizer lets a high-privileged user with network access hang or repeatedly crash MySQL Server and MySQL Cluster. The sources describe only a denial of service, with no code execution or data theft.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Run `SELECT VERSION();` on each MySQL Server and MySQL Cluster node and compare against the affected ranges: MySQL Server 8.4.0-8.4.12, 9.7.0-9.7.3, 26.7.0-26.7.1; MySQL Cluster 8.0.0-8.0.49, 8.4.0-8.4.12, 9.7.0-9.7.3, 26.7.0-26.7.1.

## Fix

- Move MySQL Server and MySQL Cluster to a patched release listed in Oracle's Critical Patch Update for the affected branch; the fixed version numbers are unknown from the sources.

## Timeline

- 2026-10-23T21:57:23+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-101801

## From the sources

Vulnerability in the MySQL Server, MySQL Cluster product of Oracle MySQL (component: Server: Optimizer).  Supported versions that are affected are MySQL Server: 8.4.0-8.4.12, 9.7.0-9.7.3, 26.7.0-26.7.1; MySQL Cluster: 8.0.0-8.0.49, 8.4.0-8.4.12, 9.7.0-9.7.3 and  26.7.0-26.7.1. Easily exploitable vulnerability allows high privileged attacker with network access via multiple protocols to compromise MySQL Server, MySQL Cluster.  Successful attacks of this vulnerability can result in unauthorized ability to cause a hang or frequently repeatable crash (complete DOS) of MySQL Server, MySQL Cluster. CVSS 3.1 Base Score 4.9 (Availability impacts).  CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H).

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_